Low concentration sensitization and development acceleration

ABSTRACT

A photographic element is disclosed comprised of a support having coated thereon a silver halide emulsion layer. In the emulsion layer or in a second layer adjacent to it, a development accelerating amount of a ruthenium cationic complex is included. The ruthenium complex includes a predominance of ammine and/or amine ligands.

United States Patent l l Beavers 1 Aug. 26, 1975 LOW CONCENTRATION SENSITIZATION AND DEVELOPMENT ACCELERATION [75] Inventor: Dorothy J. Beavers, Rochester, NY.

[73] Assignee: Eastman Kodak Company,

Rochester, NY

[22] Filed: Mar. II, 1974 [2!] Appl. No.: 450,263

[52] US. Cl. 96/95; 96/67; 96/!08 [5 I] Int. Cl. G03L 1/06 [58] Field of Search 96/107, I08, 95, 67, 74

[56] References Cited UNITED STATES PATENTS 8/1948 Smith I I l l l I 96/108 9/1955 Wark .C 96/I08 6/l972 Taber 96/IU7 3,748.l38 7/I973 Bissonctte I 96/663 3,765,891 IO/l973 Travis 96/50 R FOREIGN PATENTS OR APPLICATIONS I,248,530 l0/l97l United Kingdom 96/l07 Primary ExaminerMary F. Kelley Attorney, Agent, or FirmC. 0. Thomas 5 7 ABSTRACT 25 Claims, No Drawings LOW CONCENTRATION SENSITIZATION AND DEVELOPMENT ACCELERATION This invention relates to photographic materials. their preparation and use. In one aspect. this invention relates to photographic elements containing a ruthenium cationic complex having a predominance of ammine or amine ligands. In another aspect. this invention relates to photographic elements containing such com plexes and further containing an azaindene.

In one aspect. this invention is comprised of a photographic element having coated thereon at least one layer comprising a photographic silver halide emulsion. In the emulsion layer. or in a second layer adjacent thereto. is incorporated a development accelerating amount of a ruthenium cationic complex having a predominance of coordination bonds formed by ligands chosen from the class consisting of ammine and amine ligands. In one preferred form ofthis invention. the cationic ruthenium complex is present in a concentration of less than IOU mg per mole of silver. In another aspect. the present invention comprises the above described photographic element further including in or adjacent the emulsion layer at least one azaindene.

Cadmium salts have long been employed in the pho tographic field for a variety of purposes. For example. it is stated in Glafkides. Photographic Chemistry". Volume l. I958. page l that cadmium chloride can be used to increase the contrast in the silver halide emulsion. US Pat. No. 3.488.709 issued Jan. 6. I970. to Sidebotham teaches that cadmium bromide stabilizes silver halide emulsions precipitated in the pres ence of rhodium salts in that it reduces the loss of con trast and speed change upon storage and also that cad mium bromide acts to increase the contrast in a synergistic manner.

Although the concentrations of cadmium bromide taught by Sidebotham are relatively small. i.e.. to about 60 grams per mole of silver halide. the elimina tion or reduction of such cadmium salts appears to be ecologically advantageous since. during film processing. such cadmium salts are eventually washed out and may find their way into the environment.

In view of the now-recognized toxicity of cadmium and other trace metals. concern for the public health and the maintenance of a more normal ecological balance has led to a search for new means of achieving good properties in photographic compositions by utilizing relatively nontoxic materials or. where necessary. substantially reduced amounts of toxic materials. One means of achieving this is described in Product Licensing Index. Vol. I00. August. I972. publication IOOI4. wherein at least part of the cadmium salt is replaced by a water-soluble manganous salt. Despite the advantages of this development. however. a need still exists for improved photographic compositions which do not contain cadmium salts but which exhibit the increased photographic speed and the development acceleration obtainable with cadmium salts.

Smith and Trivelli US. Pat. No. 2.448.060 issued Aug. 31. I948. teach the use as sensitizers for photographic emulsions of soluble compounds of the general formula:

wherein R represents a hydrogen atom. an alkali metal atom or an ammonium radical; M represents a metal atom selected from group \III of the periodic arrangement of the elements hming an atomic weight greater than 100. i.e.. ruthenium. rhodium. palladium. osmium. iridium and platinum; and X represents a halogen atom. c.g.. a chlorine or bromine atom. Smith and 'I'ri \elli recognize that these compounds will fog photographic emulsions and. therefore. suggest the use of concentrations below that which produces any substantial fog. Quantities of from (1.8 to somewhat less than 39.4 mg of metal compound for each IOO grams of silver in the emulsion are suggested. It is to be noted that ammonium radicals are Lewis acids. whereas ammonia and amine compounds are Lewis bases. Further. in the above Smith and Trivelli compounds. the metal atom is coordinated in a complex having an overall negative charge.

In my earlier filed patent application Ser. No. 3 l 2.l59 filed Dec. 4. 1972. now abandoned. I disclosed trivalent cationic complexes of trivalent metals such as Ru(III). Cotlll) and Cr(lll) with amine or amine li' gands to be useful addcnda for lithographic silver chloride emulsions. These trivalent cationic complexes when incorporated in concentrations of from 0.2 to 5.0 grams per mole of silver are disclosed to promote increased photographic speed and development acceleration in a manner similar to the cadmium salts previously employed for this purpose. However. the contrast obtained with photographic elements utilizing rutheniumtlll) complexes was noted to be too low for use in lithographic elements. This is because ruthenium(lll) complexes when employed in the concentration levels investigated produce an elevated level of emulsion fogging.

Based upon further investigations. l have discovered unique and surprising properties for ruthenium complexes containing a predominance of ruthenium coor dination bonds formed by ammine or amine ligands. First. while cobalt( III) and chromium( III) complexes in emulsion concentrations significantly below 200 mg per mole of silver are substantially ineffective as sensitizers or development accelerators. l have found that much lower concentrations of ruthenium complexes having a predominance of amminc or amine ligand coordination bonds are surprisingly effective in providing sensitization and development acceleration. Hence. I have discovered these ruthenium complexes to be effective in a distinctly lower concentration range than that required for c0balt(lll) and chromium(lll) complexcs.

Second. although cobalt complexes are effective only where the cobalt is in its trivalent oxidation state. it is surprising that the effectiveness of ruthenium is not de pendent on its being in its trivlcnt oxidation state. Additionally. whereas cobalttlll) and chromium(lll) com plexes are disclosed in Ser. No. 3 l 2.1 59 to be sensitiz ers and development accelerators only for silver halide emulsions in which the halide consists of at least 50 mole percent chloride. the ruthenium complexes of my present invention are effective in sensitizing and devel opmcnt of silver halide emulsions generally. Whereas cobaltl III) and chromium(lll) complexes were disclosed in my earlier filed patent application only in highcontrast lith-type silver halide emulsions. I have discovered that the ruthenium complexes as herein disclosed are useful in proper concentration ranges in improving both high and low contrast emulsions. Still further. the ruthenium complexes are distinctly superior to cobalttlll) and chromium(lll) complexes when em- 3 ployed in high contrast emulsions lacking alkylenc oxide development restrainers. Additionally. the emulsions containing the rutheniunt complexes of this invention are useful with a wider range of developers than cobalt(lll) or chromiumtllll complexes. it is. ac cordingly. apparent that the ruthenium complexes are considerably more versatile in providing sensitization and development acceleration than eobalttlll) and chromium-(ll!) complexes.

The ruthenium complexes herein disclosed also exhibit unique and surprising properties as regards the ligands associated therewith. While l have found ruthe nium complexes containing only ammine or amine ligands to be distinctly superior. l have further observed that ruthenium complexes containing one or two ruthenium coordination bonds formed by ligands other than ammine or amine ligands afford substantial sensitization and development acceleration improvement and are superior to corresponding cobalt(lll) and chromiumtlll) complexes. even when differences in effective concentrations are ignored.

The ruthenium complexes herein employed not only act as sensitizers and development accelerators. but they also act to reduce the development time dependence of the characteristic H and D curves of the photographic elements in which they are incorporated. As is well appreciated by those skilled in the art. H and D characteristic curves are translated along the log F. axis as a function of development time. Shorter develop ment times show the photographic elements to be of slower speed while longer development periods show the same photographic elements to be faster. Since some variation in development times occurs as a practical matter in photographic element processing. it is desirable to manufacture photographic elements which can tolerate a substantial latitude in processing times. If a pair of identical photographic elements lacking the ruthenium complexes of this invention are processed at differing development times. they will exhibit a substantial difference in their log F. values at a reference densityv If an additional pair of photographic elements. including the ruthenium complexes employed in the practice of this invention. but otherwise identical. are processed similarly. l have discovered that a dramatically lower difference in their log E values at the reference density will be observed. Thus. the spacing between the H and D curves for the ruthenium complex containing photographic elements is compressed. This performance improvement for the photographic ele ments is typically referred to in the art as H and D curve compression or simply curve compression.

These and other unique and advantageous features of my invention will become further apparent in the following description of certain preferred embodiments:

The cationic ruthenium complexes employed in the practice of this invention comprise a ruthenium ion surrounded by certain other molecules which are referred to as ligands. The ruthenium ion is a Lewis acid; the ligands are Lewis bases. Werner complexes are well known examples of these complexes. As is well understood by those skilled in the art. ruthenium can exhibit a variety of valences. Because of their availability. ru thenium complexes incorporating ruthenium(ll) and ruthenium(lll) are preferred. although the effective ness of the cationic ruthenium complexes has not been observed to depend on the oxidation state ofthe ruthenium. While it is possible to form ruthenium complexes that are neutral li.c.. carry no net charge) or are nega 4 tively charged. such as the ruthenium complexes disclosed by Smith and Trivelli. only ruthenium con plcxcs exhibiting a net positive charge. i.e.. cationic complexes. are employed in the practice of this inveir tion.

The cationic ruthenium complexes employed in the practice of this invention include a predominance of ammine or amine ligand coordination bonds. The amine ligands include primary. secondary and tertiary amine ligands as well as diamine ligands. The amine ligands are preferably aliphatic amines and are most preferably comprised of alkyl. alkylenc and alkanol aliphatic moieties. Each aliphatic moiety preferably in cludes 6 or fewer carbon atoms. Dialkanol amines have been found particularly useful in forming bidentate ligands as have alkylene diamines. Bidentatc ligands which form with the ruthenium atom 5 to 8 membered rings have been found to produce particularly stable complexes. Exemplary preferred ammine and ligandforming compounds include ammonia. ethylene diaminc. trimethylene diamine. diethanol amine. dipropanol amine. diethylene triamine. alkyltetramines.

etc.

A minor proportion of the coordination bonds making up the cationic ruthenium complex can be provided by ligands other than ammine or amine ligands. A ruthenium(ll) and (Ill) complex can contain 1 or 2 monodentate ligands. such as water. halogen. thiocyanate. etc. or a single bidentate ligand.

Exemplary cationic ruthenium complexes useful in the practice of my invention are set forth below:

There will. of course. be anions associated with the foregoing complex cations. Any anion which does not exert undesirable effects upon the finished photographic element may be employed. Among those anions which will be found useful may be listed chloride. bromide. sulfite. sulfate. perchlorate. nitrite. nitrate. zinc bromide. tetrafluoroborate. hexafluorophosphate. thiocyanatc. dithionatc. methyl sulfonate. tolyl sulfonate. and the like.

The ruthenium complexes employed in the practice of this invention are incorporated within a silver halide emulsion or in a layer adjacent to a silver halide emul sion layer. The silver halide emulsions can comprise. for example. silver chloride. silver bromide. silver bromoiodide. silver chlorobromidc. silver chloroiodide. silver chlorobromoiodide crystals or mixtures thereof. The emulsions can be coarse or fine grain emulsions and can be prepared by a variety of techniques. eg. single jet emulsions such as those described in Trivelli and Smith. The llmmgruphir Journal. Vol. LXXIX. May. I939 (pages 33tl-338l. double jet emulsions.

such as Lippmann emulsions. ammoniacal emulsions. thiocyanate or thioether ripened emulsions. such as those described in Nict/ et al. LQS. Pat. No. 2.222.264 issued Nov. 19. 1940; lllingsworth US. Pat. No. 3.320.069 issued May 16. 1967 and McBride US. Pat. No. 3.271.157 issued Sept. 6. 1966. Silver halide emulsions can form latent images predominantly on the surface olthc silver halide grains. or predominantly on the interior of the silver halide grains. such as those described in Davey et al. US. Pat. No. 2.592.250 issued May 8. 1952; Porter et al. US. Pat. No. 3.206.313 issued Sept. l4.1965'.Berriman US. Pat. No. 3.367.778 issued Feb. 6. 1968 and Bacon et al. US. Pat. No. 3.447.927 issued June 3. 1969. If desired. mixture of such surface and internal image-forming emulsions can be made. such being described in Luckcy et al U.S. Pat. No. 2.996.382 issued Aug. 15. 1961. Silver halide emulsions can be regular grain emulsions. such as the type described in Klein and Moisar. J. Plmr. Sci.. Vol. 12. No. 5. Sept/Oct. 1964 pages 24225 1. and German Pat. No. 2.107.] 18. Negative type emulsions can be made. as well as direct positive emulsions as described in Leermakers US. Pat. No. 2.184.013 issued Dec. 19. 1939; Kendall et al. U.S. Pat. No. 2.541.472 issued Feb. 13. 1951; Schouwenaars British Pat. No. 723.019 issued Feb. 2. 1955;1llingsworth et al. French Pat. No. 1.520.821 issued Mar. 4. 1968;1llingsworth US. Pat. No. 3.501.307 issued March 17. 1970'. Ives US. Pat. No. 2.563.785 issued Aug. 7. 1951; Knott et al. U.S. Pat. No. 2.456.953 issued Dec. 21. 1948. and Land [.15. Pat. No. 2.861.885 issued Nov. 25. 1958.

The ruthenium complexes employed in the practice of this invention will produce sensitization and development acceleration when incorporated in a photographic element in one or more silver halide emulsion layers or in a layer immediately adjacent thereto in a concentration of as much as 5.0 grams per mole ofsilver. as indicated in my abovenoted earlier filed patent application. However. since fogging increases dramatically at higher concentration levels. concentrations of the ruthenium complexes below 1.0 gram per mole silver are presently contemplated.

1 have made the surprising discovery that the ruthenium complexes remain highly effective as sensitizers and development accelerators in concentration ranges of from 100 to 0.1 mg of ruthenium complex per mole of silver while their emulsion fogging characteristic is dramatically reduced. Accordingly. at concentrations below 100 mg per mole of silver. the ruthenium complexes can be employed in silver halide emulsions generally. including particularly those requiring high contrast. For most applications. I prefer to incorporate from 50 to 0.5 milligrams ruthenium complex per mole of silver. Generally. concentrations offrom about to l milligram per mole silver have been observed to be optimum concentration ranges in photographic ele ments.

In one preferred form. the photographic silver halide emulsions employed in the practice of this invention are lithographic silver halide emulsions in which the halide generally comprises at least about 50 mole percent chloride. up to about 10 mole percent iodide and any remaining halide being bromide. For convenience. these emulsions are referred to herein as lithographic silver halide emulsions. These high contrast emulsions preferably contain at least 60 mole percent chloride. less than 40 mole percent bromide and less than 5 mole percent iodide.

lfdcsired. the silver halides employed in the practice of this invention can be precipitated in the presence of a rhodium salt. as disclosed in Sidebotham LES. Pat. No. 3.488.709. cited above and British Pat. No. 775.197. Typical useful rhodium salts are. for example. rhodium chloride. rhodium trichloridc. rhodium ammonium chloride. etc. The rhodium salts can be employed in any concentration which is effective for the intended purpose. Especially good results are obtained when the concentration is from about 0.01 to about 0.35 milligram per mole of silver halide.

It is preferred that the photographic elements of this invention further comprise at least one azaindene. locted either in the photogrphic silver halide emulsion layer or in a layer immediately adjacent thereto. The azaindcne can be incorporated for the purpose of re ducing fog formation within the photographic element attributable to the presence of the cationic ruthenium complex. The azaindene also has a sensitizing effect. The azaindene will generally be present in a concentration of from about 0.2 to about 5.0 grants per mole of silver. preferably from about 0.3 to about 3.0 grams per mole of silver and. most preferably. from about 0.5 to about 1.0 gram per mole of silver. Among those azaindenes which may be employed in the practice of this invention can be listed. for example. 4-hydroxy-6-alkyll.3.3u.7-tetrazaindenes. such as. 4-hydroxy-6-mcthyll.3.3u,7-tctrazaindene. 5-carboxy4-hydroxyl .3.3u.7- tetrazaindcne. (i-methyl-l.3.3u.7'tetrazindene-4-thiol. 5.7-dimethyl-4.6-dioxo-4.5.6.7 tetrahydro l .2.3.5.7- pentazaindene. 6-phenyl-l .3 .3a.7-tetrazaindcne-4- thiol. 5-broino-4hydroxy-o-methyl-l.3.3u.7 tetrazaindene-4-thiol. 2.6-dimethyll .3.3u.7- tetrazaindene-4-thiol. 6-methyl-2-methylthio-1.3.3u.7- tctrazaindene-4-thiol. 5-ethyl-6-methyl-l .3.3a.7- tetrazaindene-4-thiol. 5-isobutyl-6-methyl- 1 .3.3u.7- tetrazaindenc-4 thiol. S-phenyll .2.3a. 4- tetrazaindene-7-thiol. 6-ethyl-5-mcthyl-l .2.3u.4- tetrazaindene-lthiol. 5methyl-1.2.3a,4- tctrazaindene-lthiol. l.2-bis(4-hydroxy-6-methyl- 1.3.3a.7-tetrazainden-2-yl)-1.2-dihydroxyethane. 1.6 bis(4-hydroxy-6-methyl-1.3.3u.7-tetrazainden-2-yl)- 2.5-dioxahexanc. l.Z-bisl4-hydroxy-6-methyll .3.3a.7- tetra2ainden-2-yl)cthane. l.4-bis(4-hydroxy-6methyll.3.3u.7-tetrazainden-2-yl)butane. 1.2.3.4-tetrakisl4- hydroxy6-methy1-l.3.3u.7-tetrazainden-2 yl)-butane. 5'amino- 7-hydroxy-2phenyl-l .2.3.4.6-pentazaindcne. 7 amino-5-mercapto-2-p-sulfophenyl-l 2.3.4.6- pentazaindene. 5-amino-2-p-carboxyphenyl-7- hydroxy-l.2.3.4.6-pentazaindene. 5.7-diamino-2- phenyl-l .2.3.4.6-pentazaindene. 7-amino-5- dimethylamino-Z-phenyl-1.2.3.4.6-pentazaindene. 5- dimethylamino-7-hydroxy-2-phenyl-l 2.3.4.6- pentazaindene. Z-p-aminophenyl-5amino-7-hydroxy 1.2.3.4.6pentazaindcne. S-aminOJ-hydroxy-Z-pmethoxyphenyl-1.2.3.4.6-pentazaindene. S-amino-Z-pchlorophenyl7hydroxy-1.2.3.4.6-pentazaindene. 5- amino-2-hydro-7-hydroxy-l.2.3.4.6-pentazaindene. 5.- 7-dihydroxy-l .2.3.4.6-pentazaindenc. 7-hydroxy-5- methyl-l.2.3.4.6-pentazaindene. 7-hydroxyl.2.3.4.6 pentazindcnc. 7-hydroxy-5 mercapto-l 2.3.4.6- pentazaindene. 7-amino-5-carboxy-methylmercaptol.2.3.4.6-pentazaindcne. 7mcrcapto 1 2.3.4.6- pentazaindene. 5 .7-dimercapto- 1 2.3.4.6- pentazaindene. 5-cthylmercapto-7-hydroxy-l.2.3.4.6- pentazaindene. 5-hydroxy-1.2.3.4.6-pentazaindene. 5- hydroxy-lmercapto-l .2.3.4.6-pentazaindene. 5- hydroxy-7-methyl-1.2.3.4.6-pentazaindene. 2.4-

7 dihydroxy-o-methyl-l.3u.7triazaindene. 4-hydroxy-5- chloro l .3.3u.7-tetrazaindene. 4hydroxy-5 iodo l.3.3u.7-tetra7.aindene. 2-methyl-4-hydroxy-6-methyl- 3.3u.7-tria/aindene and the like. These azaindenes. as

8 The silver halide emulsions of this invention can con vcniently be ortho-sensitixed or pairsensiti/ed with spectral sensitizing dyes. Sensitizing dyes useful in sensitiling these silver halide emulsions are described. for

well as others which can be employed in the practice of example. in Brooker et al US. Pat. No. 2.526.632 isthis invention. are known in the art and have been desribed. for example. in Heimbaeh et a1. U.S. Pat. No. 2.444.605 issued July 6. 1948; Allen et a1. U.S. Pat. No. 2.713.541 issued July 19. 1955; Carroll et a1. U.S. Pat. No. 2.716.062 issued Aug. 23. 1955; Allen et a1. U.S. Pat. No. 2.735.769 issued Feb. 21. 1956; Allen et al. US. Pat. No. 2.743.181 issued April 24. 1956; Tinker et al. US. Pat. No. 2.835.581 issued May 20. 1958; Reynolds U.S. Pat. No. 2.756.147 issued July 24. 1956; Tinker U.S. Pat. No. 2.852.375 issued Sept. 16. 1958'. Carroll et a1. U.S. Pat. No. 2.743.180 issued April 24. 1956'. Knott U.S. Pat. No. 2.933.388 issued April 19. 1960; Carroll et a1. U.S. Pat. No. 2.944.900 issued July 12. 1960; Saleek et a1. U.S. Pat. No. 3.432.304 issued March 11. 1969'. lshikawa et a1. U.S. Pat. No. 3.526.507 issued Sept. l. 1970;13aldock et a1. U.S. Pat. No. 3.573.056 issued March 30. 1971; British specification 1.270.734 to Konishiroku Photo Industry Company. Limited, published April 12. 1972 and Zeitsehrift Fur Wiss. Phot. 47. 2-28 (1952) and Piper U.S. Pat. No. 2.886.437 issued May 12. 1959.

The silver halide emulsion can contain any of the hydrophilic water-permeable binding materials known in the art to be suitable for this purpose. Suitable materials include gelatin. colloidal albumin. polyvinyl compounds. cellulose derivatives. acrylamide polymers. etc. Mixtures of these binding agents can also be used. The binding agents for the emulsion layer of the photographic element can also contain dispersed polymer ized vinyl compounds. Typical synthetic polymers in elude those described in Nottorf U.S. Pat. No. 3.142.568 issued July 28. 1964; White U.S. Pat. No. 3.193.386 issued July 6. 1965; Houck et a1. U.S. Pat. No. 3.062.674 issued Nov. 6. 1962; Houck et a1. U.S. pat. No. 3.220.844 issued Nov. 30. 1965'. Ream et a1. U.S. Pat. No. 3.287.289 issued Nov. 22. 1966'. and Dykstra U.S. Pat. No. 3.411.911 issued Nov. 19. 1968. Other vehicle materials include those water-insoluble polymers of alkyl acrylates and methacrylates. acrylic acid. sulfoalkyl acrylates or methacrylates. those which have crosslinking sites which facilitate hardening or curing as described in Smith U.S. Pat. No. 3.488.708 issued Jan. 6. 1970. and those having recurring sulfobetaine units as described in Dykstra Canadian Pat. No. 774.054. The vinyl polymers are generally em' ployed in concentrations in the range of about to about 80 percent. most often concentrations at least 50 percent. by weight. based on the weight of the binding agent. Silver halide emulsions wherein the binding agent contains dispersed polymerized vinyl compound provide particularly good results in eliminating drag streaks and dot distortions in lithographic materials.

The silver halide emulsions can be sensitized using any of the well known techniques in emulsion making. for example. by digesting with naturally active gelatin or various sulfur. selenium. tellurium compounds and- /or gold compounds. The emulsions can be sensitized with salts of noble metals ofGroup Vlll ofthe Periodic Table which have an atomic weight greater than 100. The emulsions can also contain addenda which increase speed and/or contrast such as quaternary ammonium salts. thioether sensitizers or combinations thereof.

sued Oct. 24. 19501Sprague U.S. Pat. No. 2.503.776 issued Apr. 11. 1950; Brooker et a1. U.S. Pat. No. 2.493.748 issued Jan. 10. 1950; and Taber et al. U.S. Pat. No. 3.384.486 issued May 21. 1968. Spectral sensitizers which can be used include the cyanines. mero cyanines. complex (trior tetranuclearl cyanines. holopolar cyanines. styryls. hemicyanines (e.g.. enamine cyanines). oxonols and hemioxonols.

In one preferred form. the silver halide emulsion can contain development modifiers that function as restrainers in silver halide emulsions requiring high contrast. such as lithographic silver halide emulsions. It is preferred to employ alkylcne oxides in the emulsion for this purpose. Typical useful alkylene oxides include polyethylene glycol. polyethylene glycol oleyl ether. polyethylene glycol eetyl ether. polyethylene oxide derivatives. block copolymers. such as those comprising blocks of polyoxypropylene. polyoxyethylene and the like. water-soluble organosilicone polyalkylenoxide polymers and the like. The alkylene oxide polymer can be used in any concentration effective for the intended purpose. When the alkylene oxide polymer is present in the photographic element. good results are obtained when the concentration is less than about 2 grams per mole of silver in the silver halide emulsion. A preferred concentration range for the polymer in this embodiment is from about 10 to about 800 mg per mole of silver in the silver halide emulsion.

Where it is desired to incorporate the cationic ruthe nium complex in a lithographic silver halide emulsion. it is. of course. recognized that one or more cobalt( 111) or chromium(lll) cationic complexes can additionally be incorporated into the emulsion to supplement the action ofthe cationic ruthenium complex in sensitizing or accelerating development. These cobaltl Ill) and chromium(lll) cationic complexes are fully described in my previously filed patent application. noted above. The cobalt( Ill 1 and chromium( lll) complexes are octahedral complexes formed by the metal atom acting as a Lewis acid with other associated molecules or ligands acting as Lewis bases. These complexes have coordination numbers of 6. The cohalttlll) and chromium(lll) cationic complexes useful in the practice of this invention in combination with cationic ruthenium complexes are formed entirely of ammine or amine ligands. which can be identical to those previously described as useful in the ruthenium complexes. The cobalt( 11]) and chromium(lll) cationic complexes are useful in concentration ranges of from 0.2 to 5.0 grams per mole of silver. preferably from about 0.3 to about 3.0 grams per mole of silver. and most preferably from about 0.5 to about 1.0 gram per mole silver. The cobalt(lll) and chromium(lll) complexes can be located directly within an emulsion layer or layers or in one or more layers immediately adjacent thereto. similarly as the ruthenium complexes.

The silver halide emulsions of this invention can also contain conventional addenda such as gelatin plasticizers. coating aids. antifoggants and hardeners as described in Product Licensing Index. Vol. 92. December. 1971. publication 9232. pages 107-110.

As is well understood by those skilled in the art. the photographic emulsions above described can be coated 9 onto a photographic support to form one or more silver halide emulsion layers. One or more nonimaging layers can also be coated onto the support along with the silver halide emulsion layer or layers. The nonimaging layers can take the form of subbing layers. interlayers and/or overlayers of conventional character. Where the cationic ruthenium complex is to be incorporated in a nonimaging layer adjacent to a silver halide emul sion layer. it is preferred that the nonimaging layer be comprised of a hydrophilic. waterpermeablc binding material similar to those described in connection with the silver halide emulsions.

The layers coated onto the photographic supports can be coated by various coating procedures including dip coating. air knife coating. curtain coating. or extrusion coating using hoppers of the type described in Beguin US. Pat. No. 2.681.294 issued June 15. 1954. If desired. two or more layers can be coated simulta neously by the procedures described in Russell U.S. Pat. No. 2.761.791 issued Sept. 4. 1956; Huges U.S. Pat. No. 3.508.947 issued Apr. 28. 1970; Wynn British Pat. No. 837.095 published June 9. 1960'. and Herzhof et :11. British Pat. No. 1.208.809 published Oct. 14. 1970. Also. silver halide layers can be coated by vacuum evaporation as described in British Pat. No. 968.453 published Sept. 2. 1964. and LuValle et al. U.S. pat. No. 3.219.451 issued Nov. 23. 1965.

The photographic layers. including silver halide emulsion layers and other layers of the photographic element. can be coated on a wide variety of supports. Typical supports include cellulose nitrate film. cellulose acetate film. polytvinyl acetal) film. polystyrene film. poly(ethylene terephthalate) film. polycarbonate film and related films or resinous materials. as well as glass. paper. metal and the like. Typically. a flexible support is employed. especially a paper support. which can be partially acetylated or coated with baryta and/or an alpha-olefin polymer. particularly a polymer of an alpha-olefin containing 2 to 10 carbon atoms. such as polyethylene. polypropylene. ethylenebutene copolymers and the like.

The ruthenium complexes. azaindenes and other addenda employed in the practice ofthis invention can be incorporated into the compositions forming the layer prior to coating or can be incorporated in a suitable solvent and added to the photographic element after coating. In most instances. water is the preferred solvent. The addenda can be added using various procedures. including those described in Collins el al. U.S. Pat. No. 2.912.343 issued Nov. 10. 1959; McCrossen et al. U.S. Pat. No. 3.342.605 issued Sept. 19. 1967; Audran U.S. Pat. No. 2.996.287 issued Aug. 15. 1961. and Johnson et al. U.S. Pat. No. 3.425.835 issued Feb. 4. 1969.

In addition to photographic imaging. including forming images of high contrast of the type used for exposing lithographic printing plates. the silver halide photographic elements ofthis invention can be used for making lithographic printing plates such as by the colloid transfer of undeveloped and unhardened areas of an exposed and developed emulsion to a suitable support as described in Clark et al US. Pat. No. 2.763.553 issued Sept. 18. 1956; to provide a relief immage as described in Woodward U.S. Pat. No. 3.402.045 issued Sept. 17. 1968. or Spencer U.S. Pat. No. 3.053.658 issued Sept. ll. 1962; to prepare a relief printing plate as described in Baxter et al. US Pat. No. 3.271.150 iss'ued Sept. 6. 1966'. to prepare a silver salt diffusion transfer plate as described in Hcpher et al. British Pat.

10 No. 934.691 issued Aug. 21. 1963. and Agfa British Pat. No. 883.846 issued Dec. 6. 1961; to provide an element which does not require washing or etching as described in Yackel et al. U.S. Pat. No. 3.146.104. reissue 25.885.

Although not critical to the present invention. it will be very convenient. and thus preferred. if a continuous method is employed for processing the exposed high contrast photographic elements. in such a method. the element is processed in one continuous motion by transporting it into and out of at least one processing solution in the manner shown. for example. by U.S. Pat. Nos. 3.025.779 of Russell and Kunz issued March 20. 1962; 3.078.024 of Sardeson issued Feb. 19. 1963; 3.122.086 of Fitch issued Feb. 25. 1964; 3.149.551 of Cramer issued Feb. 22. 1964; 3.156.173 of Meyer issued Nov. 10. 1964; and 3.224.356 of Fleishcr and Hixon issued Feb. 21. 1965.

It is preferred. where the photographic elements are intended to produce high contrast images upon exposure. that they be developed in developers containing one or more amines and/or amine derivatives. A particularly desirable developer composition is described in Masseth U.S. Pat. No. 3.573.914 which comprises a developing agent. a carbonyl bisulfite-amine condensation product. and at least about 0.075 mole of free amine per liter of developer composition.

The developing agents which can be employed in these developer compositions can be any of those suitable for the intended purpose. Suitable silver halide developing agents. for example. include the dihydroxy benzenes. such as hydroquinone. chlorohydroquinone. bromohydroquinone. isopropylhydroquinone. toluhydroquinone. methylhydroquinone. 2.3- dichlorohydroquinone. 2.5-dimethylhydroquinone. 2.3-dibromohydroquinone. 1.4-dihydroxy-2- acetophenone-Z.5-dimethylhydroquinone. 2.5- diethylhydroquinone. 2.5di-p-phenethylhydroquinone 2.5-dibenzoylaminohydroquinone. 2.5 diaeetaminohydroquinone. etc. Esters of such com pounds. e.g.. formates and acetates. can also be employed. These developing agents can be used alone or in any combination and can be employed in any concentration which is effective for development. A suitable concentration for the developing agent is from about 0.05 to about 0.50 mole per liter of developer compostion and is preferably from about 0.10 to about 0.30 mole per liter of developer composition.

The carbonyl bisulfiteamine condensation products which can be used in this developer composition are preferably formaldehyde bisulfitc-amine condensation products. such as sodium-2- hydroxyethylaminomethane sulfonate. odium-2 hydroxypropylaminomethane sulfonate. sodium'Lldimethyl-Z-hydroxylaminomcthanc sulfonate. sodium- 1 .1-bis(hydroxymethyl)ethylaminomethane sulfonate. sodium-tristhydroxymethyl)methylaminomethane sulfonate. sodium-3-hydr0xypropylaminomethane su1fonate. sodium-bist2-hydroxyethyl)aminomethane sulfonate. sodium-N.N-bis(2 H lhydroxylpropyllaminomethane sulfonate. sodium-N- isopropyl-N-( 2 hydroxyethyl )aminomethane sulfonate. sodiumN-etbylN( Z-hydroxyethyl )aminomethane sulfonate. and sodium-N methylN-(2 hydroxycthyl)aminomethane sulfonate. The carbonyl bisulfite-amine condensation products can be used alone or in any combinations and can be employed in any concentration which is effective to provide a low l 1 level of sullite ion for the developer composition. A suitable concentration for the carbonyl bisultitc-amine condensation product is from about to about 1.0 mole per liter ol liquid developer composition and is preferably from about 0.25 to about 0.50 mole per liter of liquid developer composition.

The carbonyl bisulfite-amine condensation product can be added to the developer composition as a sepa rate compound or formed in situ. Methods for preparing these compounds are disclosed, for example. in U.S. Pat. No. 2.388.816 of Bean issued Nov. 13. 1945.

The free or uncombined amine compounds which can be employed in these developer compositions include primary and secondary amines such as 2- aminocthanol. l-amino-Z-propanol. 2amino-2-methyll-propanol. 2-amino-2-methyl-l.3propanediol. 2- amino-2( hydroxymethyl )-l ,3-propanediol. 3aminol propanol. 2-2'-iminodietbanol. di-iso-propanolamine. Lisopropylaminoethanol. 2-ethylaminoethanol. methylaminoethanol, etc. These amines can be used alone or in any combination and should be employed in a concentration of at least about 0.075 mole per liter of developer composition. A suitable range of concentra tions for the amine compound is from about 0.075 to about 3.0 moles per liter of developer composition and is preferably from about 0.20 to about 0.90 mole per liter of developer composition. The free amine present in the developer composition can be the same amine used to prepare the carbonyl bisulfite-amine condensation product or it can be a different amine.

In addition to employing developers of the type disclosed in the above-cited Masseth patent. it is recognized that the photographic elements of this invention can be developed with conventional photographic developers exhibiting a pH in the range of from about 9 to l3. These developers are typically rendered basic by inorganic solutes. such as alkali metal hydroxides, carbonates. phosphates. silicates. etc. The developer also preferably contains at least a 0.001 molar concentration of a stabilizer. such as an alkali metal or amine bisulfitc. The developing agent can take the form of ascorbic acid or a polyhydroxybenzene. such as pyrogallol or any of the hydroquinoncs noted above in the Masscth developers. Developing agent concentrations of from 0.0] to 0.5 mole ofdeveloping agent per liter of developer are typically preferred. Other conventional developer addenda can. of course. also be incorporated. if desired.

My invention is further illustrated by the following examples.

EXAMPLES 1 THROUGH 6 A fine grain silver chlorobromoiodide gelatin emulsion containing 90 mole percent chloride. 9 mole percent bromide and 1 mole percent iodide is chemically sensitized with sulfur and gold compounds. After the emulsion is heated to obtain optimum sensitivity. the emulsion is divided into equal portions. and Ru(NH;;)..-Cl;; is added in various concentration levels. herein expressed in grams of ruthenium complex per mole of silver in the photographic element. The emul sion samples are then coated on a film support at a coverage of 50.5 mg silver/dm and 50.5 mg of gelatin/din? The coated samples are then identically exposed and processed in a Kodak developer. 0-85. Table ll summarizes the observed results.

From Table ll it is apparent that the ruthenium complex greatly increases the speed ol'the emulsion and decreases the required time of development. It is extremely surprising that the use of I00 mg per mole of silver of ruthenium complex provides even higher speeds than using 500 mg per mole of silver.

EXAMPLES 7 THROUGH l0 The procedure of Examples l through 6 was repeated using as an antiloggant an azaindene (Compound B). The results are summarized in Table lll.

Table lll Example Compound Development Fresh Results No. (g/m) Time lSec.) Speed Fog Control none I00 .05 7 0.05 IA) l0 3. .04

l.t)0 (Bl X 0.05 IA) Z0 39] .l3

l.()0 l B J 0.l IA) [0 Si .09

10 (BI l0 0.l 1A) 20 Nil .09

The combination of a ruthenum complex and an azaindene is beneficial since an improvement is observed in the fog-speed relationship when compared to coatings in Table ll containing only the ruthenium complex.

EXAMPLES ll THROUGH 13 Photographic elements were prepared by the same general procedures described in Examples 1 through 6. except that poly(ethylene oxide) as described in U.S. Pat. No. 2.944.900 was incorporated in the emulsion coatings in a concentration of 0.25 gram per mole of silver. The photographic elements were processed in a hydroquinone developer. Development times of 90 sec onds were employed in each instance to determine speed and fog for the emulsions. To determine the compression of the characteristics curves additional development times of l.() minute and 2.75 minutes were employed and the development procedures employed were those described in Masseth U.S. Pat. No. 3.573.914, Example I. using Developer A thereof. The greater the curve compression. of course. the less the difference in the log E values at the faster and slower development times. The results are summarized in Table IV.

Table lV-continued Table V-continued lwamplc ('ompound Fresh lcsts L'ompression bxamplc Compound Fresh Rcstllls No. ting/mole) Speed Fog log I: No. ting/mole) Speed log t: In 1C) H2 .04 (Min log t-; t4 tort-1| 57 .08 t to ID) 65 .05 0.80 log t-I Compound F: [RutllttNH:(H;('H NH l/nlir, Compound i [Rut NH ;I.()HL'I lfllllj] NR No value recorded Compound I) [Rut NH.l- S(" ll[('H.,S().l

To provide a comparision of curve compression per t0 EXAMPLES THROUGH l lormance of cobalttlll) and chromiumtlll) complexes. Rmhenium complexes were incorporated into d lb S P 'f elements were preparcd. as lithographic silver chloride emulsion containing 200 m Exlmp ch 1 thrfwgh one mf mg of oleic ether of polyethylene glycol (molecular l cubfmuln Chlondc one comunmg l weight 1540) per mole of silver halide. with and withmmfi l perchwmle two lmkmg any out azaindene being present. The excellent speed and Cobdh Chmm'um or ruthcmum Addenda These inter acceleration obtained with these addenda are summa wcrc prepared for comm] purposes' The cgbamm) rized below in Table VI in Developer A (containing a and chronl'umllm complexes were both prawn} m diethanolamine and bisulfite addition complex) and concentrations of 100 mg ofcomplex per mole of silver Developer B (a typicm lithographic developer) Kodak halide. Employing the development and curve com- Developer Table VI Example Addenda Relative Development No. lg/molel Speed Gamma Fog Acceleration Developer A. l'& minv at 80F (Tray) Control St) 9.2 0.03

[5 it) mg (A) 372 [0.5 0.06 excellent l6 l0 mg (A) +l2l9 [(1.2 0.l[l excellent 0.5 g (F) 17 Ill mg (E) 83 10.4 0.03 good IX It] mg 1E) 33t 10.5 0.03 good 0.5 g/m (F) Developer B. 2% min. at 68F tTrayI Control 224 8.4 (MM not tested 15 it) mg (Al 38) 11),] 0.03 not tested to It) mg (AI +l Zllt) 9.2 (1.03 not tested as g tFl l7 l0 mg (El 146 9.7 (H13 not tested l8 l0 mg (E) -H H14 ltLo 0.03 not tested 0.5 g/m IF) Compound l- 5Bromw-t-hydroxy-h-mcth ll,fljaJ-tctralaindenc pression examination procedures described above. the photographic element containing the cobalt(lll) complex exhibited a curve compression of I06 log E, which was identical to that of the control photographic element processed with it. The chromium(lll) complex similarly processed exhibited a curve compression of L36 log F. as compared to a curve compression of 1.26 log E for the control photographic element processed along with it. This illustrated that neither the cobalt- (lll) nor chromiumtlll) complexes were capable of providing significant curve compression at the concentration level of 100 mg per mole of silver halide. whereas the ruthenium complexes surprisingly exhibited very significant curve compression capabilities at one tenth this concentration level.

EXAMPLE l4 Table V lixamplc (ompound Fresh Results No (mg/mole) Speed Fog Control none 44 NR EXAMPLES 19 AND 20 A silver chlorobromoiodide (:9:1 mole ratio) emulsion is prepared using the double jet technique. The potassium chloride. potassium bromide and potassium iodide solution contained 0.15 milligram of rhodium ammonium chloride per mole of silver halide. The emulsion was sulfur and gold sensitized and heat finished to optimum sensitivity. The emulsion was then divided into equal portions and Ru(NH Cl was added to the photographic element in various concentration levels. herein expressed in milligrams of ruthenium complex per mole of silver. The emulsion samples were then coated on a film support at a coverage of 50.5 mg of silver/dm and 50.5 mg of gelatin/dm The coated samples were then identically exposed and processed for 2% minutes at room temperature in Kodak Developer D-85. Table Vll summarizes the observed results:

15 From Table V11 it is apparent that the ruthenium complex greatly increases speed and contrast in rhodium containing silver halide emulsions. When an azaindcne (Compound F) is added to Example 19 and 20 a further increase in speed is observed.

EXAMPLES 21 AND 22 Table V111 Example Compound Compound Fresh Results No. tG) gm/mole (A1 ing/mole Speed 7 Fog Control 1.0 v 1110 8.6 .02 20 7.9 200 6,4 .05 21 0.6 3.2 214 7.5 .113 22 0.4 4.7 234 8.1 ,04

Compound (i lnstclhylenediamtneIcohalttllllchloridc From Table V111 it can be seen that a combination of a cobalt complex and a ruthenium complex provides higher speed than either complex employed alone.

EXAMPLE 23 Ammonium hexachloropalladite and potassium tetrachloropalladite were tested in a similar manner as described in Examples 1-6 It was found that they did not increase speed or development acceleration.

The invention has been described in detail with par ticular reference to preferred embodiments thereof. but it will be understood that variations and modifica tions can be effected within the sprit and scope of the invention.

1 claim:

1. A photographic element comprising a support having coated thereon at least one layer comprising a photographic silver halide emulsion and in said layer or in a second layer coated adjacent thereto a ruthenium cationic complex including at least four ligands chosen from the class consisting of ammine and amine ligans. said ruthenium cationic complex being present in a concentration of at least 0.1 mg. but less than l gram per mole of silver.

2. A photographic element according to claim 1 in which said element contains from 100 to 0.1 mg of said ruthenium complex per mole of silver.

3. A photographic element according to claim 2 in which said element contains from 50 to 0.5 mg of said ruthenium complex per mole of silver.

4. A photographic element according to claim 3 in which said element contains from 20 to I mg of said ru' thenium complex per mole of silver.

5. A photographic element according to claim 1 in which said silver halide emulsion layer or said second adjacent layer contains an azaindenc antifoggant.

6. A photographic element according to claim 5 in which said azaindene is a tetraazaindene.

l6 7. A photographic element according to claim 1 in which said element contains an alkylcne oxide develop ment restraincr.

8. A photographic element according to claim 1 in 5 which said ruthenium complex is a hex-acoordinated divalent or trivalent cationic complex.

9. A photographic element according to claim 1 in which said ruthenium complex includes at least five or six ammine or amine ligands.

10. A photographic element according to claim 9 in which said ammine and amine ligands are chosen from the class consisting of ammine ligands and aliphatic amine ligands containing six or fewer carbon atoms.

II. A photographic element according to claim 10in which said amine ligands are chosen from the class consisting ofethylenc diamine. trimethylane diaminc. diethanol amine and dipropanol amine ligands.

12. A photographic element according to claim 1 in which said ruthenium complex includes ligands in addition to said ammine or amine ligands chosen from the class consisting o1 water. halogen and thiocyanate ligands.

13. A photographic element according to claim 1 in which said amine ligands are chosen from the class con sisting of aliphatic amine ligands containing six or fewer carbon atoms.

14. A photographic element comprising a support having coated thereon a high contrast lithographic silver halide emulsion containing at least 50 mole percent silver chloride and in said emulsion layer or in a layer coated adjacent thereto from 100 to 0.1 mg per mole of silver of a hexacoordinated ruthenium cationic com plex inlcuding at least four ligands chosen from the class consisting of ammine ligands and aliphatic amine ligands containing six or fewer carbon atoms. and an azaindene antifoggant.

15. A photographic element according to claim 14, in which said lithographic sliver chloride emulsion is comprised of silver halide grains in which the halide conisists of at least 50 mole percent chloride. up to about 10 mole percent iodide and any remaining halide being bromide.

16. A photographic element according to claim 14 in which said ruthenium complex is present in a concentration of from 50 to 0.5 mg per mole of silver.

17. A photographic element according to claim 16 in which said ruthenium complex is present in a concentration of from 20 to l mg per mole of silver.

18. A photographic element according to claim 14 in which said silver halide emulsion incorporates a rhodium salt.

19. A photographic element according to claim 14 in which said silver halide emulsion layer or said second adjacent layer contains a tetrazaindene antifoggant.

20. A photographic element according to claim 14 in which said silver halide emulsion layer or said second adjacent layer contains a cationic cobalt(111) complex having amine or ammine ligands.

21. A photographic element comprising a support having coated thereon a high contrast lithographic sil ver halide emulsion containing at least 50 mole percent silver chloride and in said emulsion or in a layer coated adjacent thereto 100 to 0.1 mg per mole of silver of a hexacoordinated ruthenium cationic complex including at least four ligands chosen from the class consisting of ammine ligands and aliphatic amine ligands containing six or fewer carbon atoms; and

18 any remaining silver halide being a silver bromide and in said emulsion or in a layer adjacent thereto 20 to l mg per mole of silver of a hexammine ruthe nium cationic complex: ()3 to 3.0 grams per mole ol silver of a hexammine cohaltUIl) cationic complex; and 0.3 to 3.0 grams per mole of silver of 5-hromo 4- hydroxy-fimethyl l 3.3a, 7-tetrazindenev 25. A photographic element according to claim 1 in which said photographic silver halide emulsion is a negative-type emulsion 

1. A PHOTOGRAPHIC ELEMENT COMPRISING A SUPPORT HAVING COATED THEREON AT LEAST ONE LAYER COMPRISING A PHOTOGRAPHIC SILVER HALIDE EMULSION AND IN SAID LAYER OR IN A SECOND LAYER COATED ADJACENT THERETO A RUTHENIUM CATIONIC COMPLEX INCLUDING AT LEAST FOUR LIGANDS CHOSEN FROM THE CLASS CONTAINING OF AMMINE AND AMINE LIGANS, SAID RUTHENIUM CATIONIC COMPLEX BEING PRESENT IN A CONCENTRATION OF AT LEAST 0.1 MG, BUT LESS THAN 1 GRAM PER MOLE OF SILVER.
 2. A photographic element according to claim 1 in which said element contains from 100 to 0.1 mg of said ruthenium complex per mole of silver.
 3. A photographic element according to claim 2 in which said element contains from 50 to 0.5 mg of said ruthenium complex per mole of silver.
 4. A photographic element according to claim 3 in which said element contains from 20 to 1 mg of said ruthenium complex per mole of silver.
 5. A photographic element according to claim 1 in which said silver halide emulsion layer or said second adjacent layer contains an azaindene antifoggant.
 6. A photographic element according to claim 5 in which said azaindene is a tetraazaindene.
 7. A photographic element according to claim 1 in which said element contains an alkylene oxide development restrainer.
 8. A photographic element according to claim 1 in which said ruthenium complex is a hexacoordinated divalent or trivalent cationic complex.
 9. A photographic element according to claim 1 in which said ruthenium complex includes at least five or six ammine or amine ligands.
 10. A photographic element according to claim 9 in which said ammine and amine ligands are chosen from the class consisting of ammine ligands and aliphatic amine ligands containing six or fewer carbon atoms.
 11. A photographic element according to claim 10 in which said amine ligands are chosen from the class consisting of ethylene diamine, trimethylane diamine, diethanol amine and dipropanol amine ligands.
 12. A photographic element according to claim 1 in which said ruthenium complex includes ligands in addition to said ammine or amine ligands chosen from the class consisting of water, halogen and thiocyanate ligands.
 13. A photographic element according to claim 1 in which said amine ligands are chosen from the class consisting of aliphatic amine ligands containing six or fewer carbon atoms.
 14. A photographic element comprising a support having coated thereon a high contrast lithographic silver halide emulsion containing at least 50 mole percent silver chloride and in said emulsion layer or in a layer coated adjacent thereto from 100 to 0.1 mg per mole of silver of a hexacoordinated ruthenium cationic complex inlcuding at least four ligands chosen from the class consisting of ammine ligands and aliphatic amine ligands containing six or fewer carbon atoms, and an azaindene antifoggant.
 15. A photographic element according to claim 14, in which said lithographic sliver chloride emulsion is comprised of silver halide grains in which the halide conisists of at least 50 mole percent chloride, up to about 10 mole percent iodide and any remaining halide being bromide.
 16. A photographic element according to claim 14 in which said ruthenium complex is present in a concentration of from 50 to 0.5 mg per mole of silver.
 17. A photographic element according to claim 16 in which Said ruthenium complex is present in a concentration of from 20 to 1 mg per mole of silver.
 18. A photographic element according to claim 14 in which said silver halide emulsion incorporates a rhodium salt.
 19. A photographic element according to claim 14 in which said silver halide emulsion layer or said second adjacent layer contains a tetrazaindene antifoggant.
 20. A photographic element according to claim 14 in which said silver halide emulsion layer or said second adjacent layer contains a cationic cobalt(III) complex having amine or ammine ligands.
 21. A photographic element comprising a support having coated thereon a high contrast lithographic silver halide emulsion containing at least 50 mole percent silver chloride and in said emulsion or in a layer coated adjacent thereto 100 to 0.1 mg per mole of silver of a hexacoordinated ruthenium cationic complex including at least four ligands chosen from the class consisting of ammine ligands and aliphatic amine ligands containing six or fewer carbon atoms; and 0.2 to 5.0 grams per mole of silver of a hexacoordinated cobalt or chromium(III) cationic complex.
 22. A photographic element according to claim 21 in which said silver halide emulsion or said adjacent layer contains a tetrazaindene.
 23. A photographic element according to claim 22 in which said ruthenium complex and said cobalt(III) complex are both hexammine complexes.
 24. A photographic element comprising a support having coated thereon a high contrast lithographic silver halide emulsion containing at least 50 mole percent silver chloride, up to 10 mole percent silver iodide and any remaining silver halide being a silver bromide and in said emulsion or in a layer adjacent thereto 20 to 1 mg per mole of silver of a hexammine ruthenium cationic complex; 0.3 to 3.0 grams per mole of silver of a hexammine cobalt(III) cationic complex; and 0.3 to 3.0 grams per mole of silver of 5-bromo-4-hydroxy-6-methyl-1,3,3a, 7-tetrazindene.
 25. A photographic element according to claim 1 in which said photographic silver halide emulsion is a negative-type emulsion. 